Modular Watercraft Assembly

ABSTRACT

A modular watercraft assembly and apparatus. In one embodiment, the watercraft assembly includes a divided floatation support member that provides buoyant support. The divided floatation support member includes a first pontoon and a second pontoon that are both longitudinally extensible pontoons. The longitudinally extensible pontoons each include at least two substantially rigid tubes that are telescopically extensible and collapsible in an annularly nested manner. The assembly further includes multiple substantially rigid cross members and multiple cross member fasteners for transversely coupling the cross members between the first and second pontoons of the divided floatation support member. When assembled the watercraft assembly provides buoyant support for a variety of different craft designs including but not limited to a sailing catamaran, a pedaloe, and others.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to pontoon-type watercraft, andin particular to a watercraft assembly that may be readily assembled anddisassembled prior to and following usage. More particularly, thewatercraft assembly of the present invention includes a pair of pontoonseach comprising annularly collapsible extruded tubes enabling theassembly to be stored and transported in a convenient, compact manner.Still more particularly, the present invention relates to a modularwatercraft assembly which form a universal platform from which a varietyof different watercraft can be assembled.

2. Description of the Related Art

Many forms of recreational watercraft are known. Variations inpropulsion mechanisms include sail driven, manual oar driven, motorizedand engine driven designs. A corresponding variety of hull and deckdesigns accommodate the different propulsion mechanisms. Ultimately, themany hull and propulsion designs have been developed to achieve adesired recreational usage. Some vessel designs are highly specializedfor a specific use. Examples include speedboats having a characteristiccigar shaped hull design and high output engine-driven propulsion trainsas well as wind surf boards and jet skis. Other recreational watercraftdesigns accommodate a variety of recreational uses such as fishing,skiing, and touring. A standard craft accommodating multiple uses is asingle hull craft powered by a inboard or outboard engine.

Significant issues for most boat owners include storage and transport ofthe craft to and from water recreation sites. Most sizable boats requiretrailer transport which adds substantial additional complexity,inconvenience, and cost to any boating excursion. Furthermore, manyboats used for cruising, fishing, skiing, etc., are 12 feet and longerand therefore require storage space comparable to or often greater thanthat required for a parked car. Given the impossibility or inconvenienceof storing a watercraft in an enclosed garage and the typical inability,due to lack of property space or neighborhood restrictions, to store thecraft outside an enclosure, craft owners are often compelled to seekremote storage. Typical remote storage sites include marinas or out ofwater storage at outdoor storage lots. In addition to substantialstorage expense, remote storage may only address the transport issueswith respect to only the single storage/usage site.

Inflatable craft and smaller dimension fixed hull designs alleviate manystorage and transport issues. However, smaller craft impose limited usesand limit the numbers of passengers that may be accommodated. Inflatablecraft also address storage and transport issues and may accommodate asubstantial number of passengers. However, conventional inflatablewatercraft have performance issues relating for example to lack of astable deck and vulnerability to being breached by rough handling orcontact with sharp objects. Furthermore, as with other hull designs, theusages of inflatable type watercraft are generally limited in scope.

Pontoon type watercraft have enjoyed explosive growth in popularity as arecreational vessel ideally suited for accommodating multiple passengersfor a variety of water sport activities and leisure. The characteristicflat platform supported by opposing pontoon floatation members providesmaximum stability and an ideally flat surface on which passengers maycomfortably sit, stand, and walk with minimal instability. Pontoon typecraft are widely utilized as a swimming or fishing platform as well asfor leisure touring.

While ideally suited for various water recreation activities, thestructural design of pontoon type craft, in terms of size and contour,pose particular problems relating to the aforementioned transport andstorage issues faced by boat owners. Pontoon type craft are “boxy” andgenerally large, making them particularly inconvenient to tow on atrailer and store. Furthermore, as with other watercraft designs,conventional pontoon design is structurally fixed and is thereforelimited in the number of different watercraft recreational activitieswhich can be accommodated.

It can therefore be appreciated that a need exists for an improved watercraft design that flexibly accommodates several widely different waterrecreation activities while overcoming issues relating to transport andstorage and other problems encountered in the prior art. The presentinvention addresses these and other needs unresolved by the prior art.

SUMMARY OF THE INVENTION

A modular watercraft assembly and apparatus are disclosed herein. In oneembodiment, the watercraft assembly includes a divided floatationsupport member that provides buoyant support. The divided floatationsupport member includes a first pontoon and a second pontoon that areboth longitudinally extensible pontoons. The longitudinally extensiblepontoons each include at least two substantially rigid tubes that aretelescopically extensible and collapsible in an annularly nested manner.The assembly further includes multiple substantially rigid cross membersand multiple cross member fasteners for transversely coupling the crossmembers between the first and second pontoons of the divided floatationsupport member. When assembled the watercraft assembly provides buoyantsupport for a variety of different craft designs including but notlimited to a sailing catamaran, a pedaloe, and others.

The above as well as additional objects, features, and advantages of thepresent invention will become apparent in the following detailed writtendescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself however, as well as apreferred mode of use, further objects and advantages thereof, will bestbe understood by reference to the following detailed description of anillustrative embodiment when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 depicts the disassembled constituent components of a watercraftassembly in accordance with one embodiment of the present invention;

FIG. 2 illustrates an assembled watercraft assembly in accordance withan alternate embodiment of the present invention;

FIG. 3 is a more detailed view depicting components of the watercraftassembly shown in FIG.2;

FIG. 4 illustrates components of a modular watercraft assembly inaccordance with an alternate embodiment of the present invention;

FIG. 5 depicts further detail of the components shown in FIG. 4;

FIG. 6 illustrates a frame clamp such as may be utilized for coupling across member to a pontoon in accordance with an embodiment of thepresent invention;

FIG. 7 depicts seal caps such as may be incorporated in the design of amodular watercraft assembly in accordance with an embodiment of thepresent invention;

FIG. 8A illustrates a sailing catamaran configuration incorporating thewatercraft assembly of the present invention;

FIG. 8B depicts a rowing shell configuration incorporating thewatercraft assembly of the present invention;

FIG. 8C depicts a pedaloe configuration incorporating the watercraftassembly of the present invention;

FIG. 8D depicts an outrigger canoe configuration incorporating thewatercraft assembly of the present invention;

FIG. 8E depicts an outrigger canoe with small outrigger pontoonconfiguration incorporating the watercraft assembly of the presentinvention;

FIG. 8F depicts a snorkel viewer configuration incorporating thewatercraft assembly of the present invention; and

FIG. 8G depicts a fishing boat configuration incorporating thewatercraft assembly of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENT(S)

The present invention is described in a preferred embodiment in thefollowing description with reference to the figures. While thisinvention is described in terms of the best mode for achieving thisinvention's objectives, it will be appreciated by those skilled in theart that variations may be accomplished in view of these teachingswithout deviating from the spirit or scope of the present invention.Furthermore, when used and unless otherwise stated, terms such as“horizontal,” “vertical,” “upper,” “lower,” “front,” “rear,” “over,” and“under,” and similar position related terms are not to be construed aslimiting the invention to a particular orientation. Instead, such termsare to be construed only on a relative basis reflecting the relativeposition and orientation of the various components shown in theaccompanying depicted embodiments.

The present invention is generally directed to a watercraftcharacterized in one aspect as having a divided floatation support meanssuch as is used in pontoon-type craft. In this aspect the watercraft ofthe invention comprises a pair of elongated pontoons coupled together bydetachable cross members. The divided floatation support providesoptimally stable support for a deck surface and which is substantiallyresistance to sources of instability such as passenger movement or otherload shifts.

While ideally suited for various water recreation activities, thestructural design of traditional pontoon-type craft, in terms of sizeand contour, pose particular problems relating to transport and storageof the craft. The present invention addresses such problems andfurthermore enhances the breadth of usage of such craft with awatercraft design that facilitates ease of transport and storage andwhich enables the craft to accommodate a wide variety of topsideconfigurations. Furthermore, the invention provides a buoyant frame onwhich a variety of different types of watercraft can be deployed from.

As depicted and explained in further detail below with reference to thefigures, the present invention is in one aspect directed to a watercraftassembly and kit that when disassembled into constituent components maybe packed in a compact manner within a portable carrying case for easeof storage and transport to and from a site of usage. Furthermore, thewatercraft assembly is designed to accommodate multiple topsideconfigurations such as may be ideally suited for different waterrecreation activities such as leisure touring, swimming, fishing, etc.Examples of such activity-specific top-side design that can beadvantageously deployed are depicted in further detail with reference toFIGS. 8A-8G.

With reference now to the figures, wherein like reference numerals referto like and corresponding parts throughout, and in particular withreference to FIG. 1, there is depicted a disassembled watercraftassembly 10 in accordance with one embodiment of the present invention.Watercraft assembly 10 generally comprises a pair of pontoons 2, a pairof cross members 4, and two pair of cross member fasteners 6. As shownin the depicted embodiment, pontoons 2 are preferably mutually discretecomponents that can be independently moved and positioned when thewatercraft is disassembled. Given the pontoon-type configuration of thewatercraft when assembled, pontoons 2 collectively comprise a dividedfloatation support member 5 that when the watercraft is assembled,provides buoyant support for the watercraft.

Cross members 4 and cross member fasteners 6 form the primary means forcoupling pontoons 2 together in the familiar parallel pontoon boatfloatation configuration. In the depicted embodiment, each of crossmembers 4 comprises a T-bar having multiple fastener holes on eachdistal end as shown in the figure. Cross members 4 are preferablyconstructed as a molded unit from a high-strength polymer or lightweightmetal alloy.

Each of cross member fasteners 6 generally comprises a coupling bracket16 and a ring clamp 14 that fits around the outer contour of arespective one of pontoons 2. During assembly of the component parts ofwatercraft assembly 10, pontoons 2 are fitted within ring clamps 14which are comprised of a wide semi-flexible band of plastic, metal orother material that is tightened around the substantiallycurvilinear-contoured outer surface of pontoons 2 either by screw orratchet action. The cross member fasteners 6 are then positioned so thatthe respective coupling brackets 16 are positioned on the top side ofpontoons 2 where they may engage the ends of cross members 4. Crossmembers 4 are then positioned so that the ends of the T-bar having themechanical fastener holes are slidably placed within the depicted slots7 within the brackets 16 where they are coupled using mechanicalfasteners 18 such as threaded bolts. When fastened in this manner, crossmember brackets 16 provide cantilevered support for the respectivelyfastened cross member 4 against the pontoons 2.

With pontoons 2 mutually coupled in a parallel, dual-pontoonconfiguration, such as that shown in the following figures, floatationsupport member 5 provides buoyant support for a passenger supportapparatus (examples depicted in FIGS. 8A-8G) supported by the topT-surface of cross members 4. When assembled, watercraft assembly 10provides a universal floatation platform ideally suited for a variety ofdifferent passenger support applications including a sailing catamaran,fishing craft, pedaloe, etc.

To facilitate ease of storage and transport, the watercraft of thepresent invention may be readily disassembled into the constituentcomponents shown in FIG. 1. In the depicted embodiment, for example, thewatercraft may be disassembled such that the lengthwise and widthwisepontoon and cross member components 2 and 4 are no longerinterconnected, thus greatly reducing the containment space required toaccommodate the assembly during transport and storage. Whendisassembled, the components of watercraft assembly 10 may beconveniently packed into one or more storage containers that may then betransported to a water recreation site, such as a lake or river, wherethe watercraft may be quickly and easily assembled using a minimum ifany hand tools.

In addition to being mutually uncoupled as well as uncoupled from crossmembers 4, pontoons 2 preferably include additional features enablingfurther compaction and/or disassembly of the watercraft assembly.Namely, at least one and preferably both of pontoons 2 comprise anelongated tube member 8 capped at each end by end caps 12. Tube members8 are preferably cylindrically or otherwise curvilinear contoured andinclude a hard (i.e., non-pliant) protective outer shell that may beconstructed of a rigid polymer or metal alloy. In one embodiment, endcaps 12 are molded parts that may be glued, welded, or otherwiseadhesively coupled onto each of the opposing ends of elongated tubemember 8. In alternate embodiments, end caps 12 are preferably fastenedto the ends of elongated tube members 8 using removable mechanicalfasteners such as threaded fasteners. The end caps reduce waterresistance and may contain an air lock equalizer (not depicted) whichallows air pressure to change as air is pumped into or release from theinner pontoon volume. As further shown in FIG. 1, cleats 24 arepreferably integrally molded to the top side of each of end caps 12.

Referring to FIG. 2, there is illustrated an assembled watercraftassembly 15 in accordance with an alternate embodiment of the presentinvention. Similar to watercraft assembly 10 depicted in FIG. 1,watercraft assembly 15 is a dual pontoon type craft generally comprisinga divided floatation support member comprising a pair of paralleldisposed pontoons 38 transversely coupled by a pair of substantiallyrigid cross members 34. Pontoons 38 each include front (i.e. bow) andrear (i.e. stern) end caps 11 and 13, respectively, which are preferablyindividually removable when watercraft assembly 15 is disassembled.

A key feature of watercraft assembly 15 is the composition of pontoons38 as comprising telescopically extensible tubes which, in the depictedembodiment, comprise a first tube 23 and a second tube 27. First andsecond tubes 23 and 27 are substantially rigid tube members that aremutually coupled in an annularly nested manner in which second tube 27is of slight smaller diameter than and slides within first tube 23.Further details depicting the slidable engagement between first andsecond tubes 23 and 27 are shown in FIG. 3. Namely, an external gasket20, which in one embodiment comprises an elastic O-ring, is disposedannularly around the outer contour of second tube 27 to provide anairtight and watertight seal at the region of engagement between gasket20 and the inner surface of first tube 23. Providing a similar airtightand watertight seal is a gasket 28 disposed annularly within the innercircumferential surface of first tube 23. Disposed as shown in FIG. 3,gaskets 20 and 28 provide a seal and bearing surface along which secondtube 27 slidably engages first tube 23 while not expressly depicted inthe figures, the depicted gaskets 20 and 28 are preferably supportedwithin a housing slot fabricated onto the corresponding tube surface.

When watercraft assembly 15 is disassembled in a manner similar to thatdepicted for the assembly shown in FIG. 1, first and second tubes 23 and27 may be telescopically collapsed so that the combined assembly, withor without end caps 11 and 13 attains a minimal length and can thereforebe more compactly stored. During assembly of the component parts ofwatercraft assembly 15, second tube 27 is extended from first tube 23 sothat the overall length of the combined assembly is determined by suchextension. The extended position, such as that depicted in FIG. 2 issecurely maintained by one or more locking mechanisms such as set screws31.

In a preferred embodiment, the extension between first and second tubes23 and 27 may be achieved by manually pulling one of the tubes withrespect to the other to achieve the desired extension. In an alternateembodiment, the pontoon assembly extension may be achieved usingpneumatic means such as by applying air pressure to the inner chamberformed within the annularly nested tubes. As illustrated in FIG. 2, eachof rear end caps 13 may include an air valve 21 through which airpressure may be applied to inflate and pressurize the inner chamberwithin the pontoons. Air valve 21 preferably also serves as an airpressure outlet or relief valve for regulating the air pressure withinthe pontoons to facilitate extension and retraction of the assembly. Inan alternate embodiment, one or both of tubes 23 and 27 contain a foamedplastic to provide floatation aid for emergency situations such as acollision or other forceful trauma that breaches the outer skin of oneor both of pontoons 38.

In the depicted embodiment, cross members 34 are disposed transverselybetween the pontoons and include curved support pads 22 through whichforce is transmitted from cross members 34 to the respective pontoons.Cross members 34 are preferably substantially rigid members having crossmember fasteners 36 designed in accordance with an alternate embodimentof the present invention.

FIG. 3 is a more detailed view depicting components of watercraftassembly 15 and particularly illustrating the constituent parts of crossmember fasteners 36. As illustrated in FIG. 3, cross member fasteners 36comprise a ratchet assembly 25 attached to a respective distal end of across member that adjusts the tension on a compression strap 26 tosecure the respective cross members 34 to the tube portion of thepontoons. Ratchet assembly 25 may be any device used to allow motion inone direction while simultaneously restricting motion in the opposingdirection to effectuate a secure coupling. In the depicted embodiment,ratchet assembly 25 includes geared ratchet spindle 29 having gear teethset off at an angle, and a pawl (not expressly depicted) that restsagainst the gears. When ratchet spindle 29 is rotated using a ratchetlever 32 in the “tighten” direction, the pawl traverses along the gearsuntil the rotation is stopped at which point the pawl rests in place tolock the assembly. Manual actuation of ratchet lever 32 controlsrotation of the spindle to tighten or loosen the assembly.

With reference to FIGS. 4-7, there are depicted various aspects of awatercraft assembly in accordance with an alternate embodiment of theinvention. Namely, FIGS. 4-7 illustrate aspects of a dual pontoonmodular watercraft assembly that includes modularly assembled pontoons.A pair of pontoons 42 is shown in FIG. 4, with the pontoons 42 depictedin states of assembly (top) and partial assembly (bottom). Each ofpontoons 42 is modularly constructed of a pair of substantially rigid,hollow tube members 40. FIG. 5 is an exploded view illustrating furtherdetail of one end of one of pontoons 42. Coupled to both ends of each oftube members 40 are a pair of seal caps which are illustrated anddescribed in further detail below with reference to FIG. 7. In thedepicted embodiment, tube member 40 a is capped at each end by seal caps52 and tube member 40 b is capped at each end by seal caps 54.

FIG. 7 depicts seal caps 52 and 54 such as may be incorporated in thedesign of a modular watercraft assembly in accordance with oneembodiment of the present invention. Both of seal caps 52 and 54 aresubstantially cylindrical members having a gas and liquid impermeablebarrier plate 49. When adhered or fastened to both ends of a tube member40, seal caps 52 and 54 prevent water from entering the inner volume ofthe tube. Seal caps 52 and 54 are preferably molded pieces that aremolded, adhered, or otherwise fastened to the cylindrical ends of tubes40.

Seal caps 52 and 54 further include mutually complementary lockingfeatures that enable the caps to be locked together so that multiple oftubes 40 can be modularly coupled end-to-end as shown in FIG. 4.Specifically, and as shown in FIG. 7 in conjunction with FIG. 5, sealcap 52 includes a pair of lugs 51 projecting from its interior annularsurface and seal cap 54 has a pair of correspondingly positioned keyholeslots 47. Lugs 51 slide within keyhole slots 47 when end cap 52 isplaced and rotated against end cap 54 thus locking the seal capstogether and forming a linkage between the respective tube members. Inthis manner, one or more such tube and seal cap assemblies can becoupled together to form pontoons such as pontoons 42.

A further aspect of the depicted embodiment is illustrated particularlywith reference to FIGS. 5 and 6. As depicted in FIG. 5, seal caps 52 and54 further comprise lip members 48 extending tangentially and laterallyfrom the top of the respective seal caps. Lip members 48 of both of sealcaps form a stable anchor point on which cross member 44 may be fastenedto the pontoon assembly. As further shown in FIGS. 5 and 6, a frameclamp 50 is formed at the ends of cross members 44. Frame clamp 50includes a lever handle 45 that pivotally actuates a latch lip 43 thatis secured over lip members 48 to secure a given end of cross member 44to a pontoon assembly.

When assembled each of the watercraft assemblies depicted in theforegoing figures provides a universal support platform ideally suitedfor deployment of a variety of activity-specific top-side watercraftconfigurations. Exemplary of such configurations are those depicted inFIGS. 8A-8G which depict several activity-specific watercraftconfigurations incorporating the watercraft support design described anddepicted above with reference to FIGS. 1-7. Specifically, FIG. 8Aillustrates a sailing catamaran configuration; FIG. 8B depicts a rowingshell configuration; FIG. 8C depicts a pedaloe configuration; FIG. 8Ddepicts an outrigger canoe configuration; FIG. 8E depicts an outriggercanoe with small outrigger pontoon configuration; FIG. 8F depicts asnorkel viewer configuration; and FIG. 8G depicts a fishing boatconfiguration incorporating the watercraft assembly of the presentinvention. As illustrated in FIGS. 8A-8G, the watercraft assemblyincludes several features such as adjustable length pontoons providinggreat flexibility in appearance and/or buoyancy characteristics. Inaddition to the standard pontoon design, monohull, catamaran & trimaranconfigurations can be deployed from the assembly.

While the invention has been particularly shown and described withreference to a preferred embodiment, it will be understood by thoseskilled in the art that various changes in form and detail may be madetherein without departing from the spirit and scope of the invention.These alternate implementations all fall within the scope of theinvention.

1. A modular watercraft assembly comprising: a divided floatationsupport member comprising a first pontoon and a second pontoon, at leastone of said first and second pontoons comprising a longitudinallyextensible pontoon, wherein said at least one longitudinally extensiblepontoon comprises at least two substantially rigid tubes that aretelescopically extensible so as to define an elongated use configurationand collapsible in an annularly nested manner so as to define ashortened storage configuration; a plurality of substantially rigidcross members; and a plurality of cross member fasteners fortransversely coupling said cross members between said first and secondpontoons of said divided floatation support member.
 2. The modularwatercraft assembly of claim 1, wherein said first and second pontoonshave a substantially curvilinear transverse outer cross section contour,and wherein said cross member fasteners include a collar member forannularly fitting over and around the outer cross section contour ofsaid first and second pontoons.
 3. The modular watercraft assembly ofclaim 1, wherein said cross member fasteners include a coupling bracketto which a cross member is fastened, said coupling bracket providingcantilevered support for the fastened cross member against one of saidfirst and second pontoons.
 4. The modular watereraft assembly of claim1, wherein said longitudinally extensible pontoon further comprises endcaps coupled to the ends of said at least two substantially rigid tubes,said end caps containing a buoyant filler material.
 5. (canceled)
 6. Themodular watercraft assembly of claim 1, wherein the at least twosubstantially rigid tubes comprise a first tube and a second tube, saidfirst tube having an outer sleeve portion that slides over said secondtube when the first and second tubes are telescopically extended orcollapsed, said modular watercraft assembly further comprising at leastone o-ring gasket disposed between the exterior surface of said secondtube and the interior surface of said first tube to form a waterimpermeable seal between the exterior surface of said second tube andthe interior surface of said first tube.
 7. The modular watercraftassembly of claim 6, further comprising a locking member for locking thefirst and second tubes in an extended position.
 8. A modular watercraftassembly comprising: a divided floatation support member comprising afirst pontoon and a second pontoon, at least one of said first andsecond pontoons comprising a longitudinally extensible pontoon, saidlongitudinally extensible pontoon comprising at least two substantiallyrigid tubes that are telescopically extensible and collapsible in anannularly nested manner; a plurality of substantially rigid crossmembers coupled between said first and second pontoon members said crossmembers comprising a curved support pad at each distal end, said curvedsupport pads resting on said first and second pontoons; and a pluralityof cross member fasteners for transversely coupling said cross membersbetween said first and second pontoons of said divided floatationsupport member, each of said plurality of cross member fastenerscomprising: a flexible compression strap; and a compression straptightening mechanism for adjustably tightening said compression straparound the outer surface of one of said first or second pontoons.
 9. Themodular watercraft assembly of claim 8, said compression straptightening mechanism comprising a hand-actuated ratchet assembly coupledto each distal end of each of said cross members.
 10. The modularwatercraft assembly of claim 8, wherein each of said first and secondpontoons further comprises an air pressure valve for inletting andreleasing air pressure from the interior volume of said first and secondpontoons.
 11. The modular watereraft assembly of claim 8, wherein saidlongitudinally extensible pontoon further comprises end caps coupled tothe ends of said at least two substantially rigid tubes, said end capscontaining a buoyant filler material.
 12. The modular watercraftassembly of claim 8, wherein the at least two substantially rigid tubescomprise a first tube and a second tube, said first tube having an outersleeve portion that slides over said second tube when the tubes aretelescopically extended or collapsed, said modular watercraft assemblyfurther comprising at least one o-ring gasket disposed between theexterior surface of said second tube and the interior surface of saidfirst tube to form a water impermeable boundary.
 13. The modularwatercraft assembly of claim 12, further comprising a locking member forlocking the first and second tubes in an extended position.
 14. Amodular watereraft assembly comprising: a divided floatation supportmember comprising a first pontoon and a second pontoon, at least one ofsaid first and second pontoons comprising a modularly assembled compoundunit comprising multiple, lengthwise attached tube members; a pluralityof substantially rigid cross members coupled between said first andsecond pontoon members said cross members comprising a frame clamp ateach distal end; and wherein each of said lengthwise attached tubemembers includes a seal cap member coupled to each distal end, said sealcap member comprising: a water impermeable plate that prevents waterfrom entering a tube member; a seal cap locking mechanism formechanically engaging to an adjacent seal cap; and a lip memberextending substantially tangentially from the outer circumferentialsurface of said seal cap, wherein said lip member is mechanicallyengaged by one of said frame clamps to affix said cross member to one ofsaid first or second pontoons.
 15. The modular watercraft assembly ofclaim 14, further comprising end caps coupled to the ends of said firstand second pontoons, said end caps containing a buoyant filler material.